TMTD added to Significant New Activity rules

Summary#

• The federal government has made Order 2026-87-22-01 Amending the Domestic Substances List.
• It adds the chemical thioperoxydicarbonic diamide ([(H2N)C(S)]2S2), tetramethyl- (CAS 137-26-8, also called TMTD) to the list of substances that trigger a requirement to notify before certain new activities. The rule takes effect 180 days after registration (registered October 9, 2026).

What it does#

• Applies the Significant New Activity (SNAc) rules under the Canadian Environmental Protection Act, 1999 to TMTD (CAS 137-26-8).
• Creates two specific situations that count as a “significant new activity” for this substance:
  • Manufacturing more than 100 kg of the substance in a calendar year.
  • Using more than 100 kg of the substance in the manufacture of liquid rubber (latex) products in a calendar year.
• Requires anyone proposing one of those activities to send detailed information to the Minister of the Environment at least 180 days before the activity starts.
• The required information must be assessed by the government within 180 days after it is received.
• The Order does not change or restrict existing uses that are already below the thresholds or were assessed as having no or limited risk.

Who's affected#

• Businesses that make TMTD in Canada.
• Companies that use TMTD to make liquid rubber (latex) products.
• Importers or downstream users who would cause Canada-wide manufacture or use of TMTD above the 100 kg thresholds.
• Researchers doing small-scale laboratory work are generally excluded if the substance meets the definition of a research and development substance in the New Substances rules.
• The notice does not clearly identify other specific groups that will be affected; if you are unsure whether your activity counts, the government offers pre-notification help.

Why it matters#

• TMTD is used in rubber manufacturing and can be released to wastewater from production sites. The government’s assessment found it is highly toxic to aquatic life.
• By requiring advance notification and information for bigger or new uses, the rule gives scientists time to assess whether a proposed new activity would raise environmental or health risks.
• If a proposed use looks risky, the government can impose controls before that use starts. This can prevent new releases or higher exposures rather than responding after the fact.
• For businesses, the main practical effect is that planning a new, larger-scale use of TMTD will require extra time and data up front (and could delay commercial activity during the government’s 180-day review). There is no fee to submit the notice, but preparing the required information could have costs.